1. Rearrange the second equation to make $z$ the subject.
z=(4−i)w∗+3i
2. Substitute $z$ into the first equation and simplify to obtain an equation in terms of $w$ and $w^*$.
2i[(4−i)w∗+3i]+w=5+7i
(8i−2i2)w∗+6i2+w=5+7i
(2+8i)w∗−6+w=5+7i
w+(2+8i)w∗=11+7i
3. Let $w = x + y\text{i}$, substitute $w$ and $w^*$ into the equation, and expand.
Let w=x+yi and w∗=x−yi, where x,y∈R.
(x+yi)+(2+8i)(x−yi)=11+7i
x+yi+2x−2yi+8xi−8yi2=11+7i
x+yi+2x−2yi+8xi+8y=11+7i
(3x+8y)+(8x−y)i=11+7i
4. Equate the real and imaginary parts to form a pair of simultaneous equations.
Equating real parts:
3x+8y=11— (1)
Equating imaginary parts:
8x−y=7— (2)
5. Solve the simultaneous equations to find $x$ and $y$, thus obtaining $w$.
From (2), y=8x−7.
Substitute into (1):
3x+8(8x−7)=11
3x+64x−56=11
67x=67⟹x=1
y=8(1)−7=1
Therefore, w=1+i.
6. Substitute $w^*$ back into the expression for $z$ to find its value.
Using w∗=1−i:
z=(4−i)(1−i)+3i
z=4−4i−i+i2+3i
z=4−5i−1+3i
z=3−2i
Answerz=3−2i, w=1+i